Home health check
Keeping this architectural feature well maintained and free of potentially dangerous blockages is essential to ensure it remains safe and in good working order
Make sure your chimney is in tip-top condition before Father Christmas comes to visit
Generally the highest point on a building, chimneys are important architectural features but often suffer from neglect, despite having the potential to cause disastrous fires and major damage should parts of the masonry come loose and fall off the property.
The flue within a chimney conducts smoke and gases away due to the warm air from the fire rising, creating an upward draught or draw. For this to happen, it must be clear of blockages, the fireplace opening must be the right size, the room must have sufficient ventilation and there must be no downdraught from outside. Before using a chimney for the first time, check it’s safe and in good working order. Always burn dry, wellseasoned wood to avoid tar deposits collecting within the flue.
Chimneys that are used must be professionally swept regularly and carbon monoxide and smoke alarms should be installed and tested monthly. Chimney repairs involve working at height, so necessitate the use of scaffolding and are generally best left to a builder who has an understanding of old buildings. ➤
Material facts
Externally, chimney stacks are particularly vulnerable to damage from wind and rain, and may decay much more quickly than other parts of the building. Internally, flues are affected by the corrosive effect of combustion gases.
BRICK, STONE AND SLATE: Separately and in combination, these materials are used to build the chimney stack and to form the mid-feathers or withes, the internal divisions between flues from different fireplaces.
LIME: Mortar and renders made from lime allow for flexibility and expansion, both important factors in chimneys. Some chimneys are finished internally with a coat of lime plaster or ‘parging’ to provide a smooth, leak-free lining.
TERRACOTTA: Chimney pots made of terracotta often terminate chimneys, sometimes providing a decorative flourish.
Warning signs
Poorly maintained flues can result in house fires and may also leak deadly gases, so the condition of the chimney stack should be checked at least annually – externally, with the aid of binoculars, and internally, where possible, from within the roof space itself.
What to look for:
● Debris in the hearth, including plaster, brick, stone and twigs
● Smoke entering the room
● Dampness around the stack in the roof space
● Staining on chimney breasts
● Eroded mortar pointing or render on the stack
● Defective flashing where chimney and roof meet
● Loose chimney pots
● Leaning stacks
Chimney repairs
Deterioration to a chimney can result in a variety of issues that may require work, ranging from the need to re-bed chimney pots, repointing and replacing individual bricks or rebuilding the stack. Action:
● Call in a bricklayer or roofer who understands old buildings.
● Ensure lime-based materials are used for repointing or rendering. Ask the lime supplier for advice on the most appropriate product and mix.
● Consult a structural engineer or surveyor where a chimney is leaning. Stability may be improved by installing a tie rod and strap connected to the roof.
Flues
The airtightness of a flue is essential for the safety of the building and its occupants. Any form of combustion may result in carbon monoxide, which has no smell but has the potential to kill. Action:
● Test the flue using a smoke pellet, available from fireplace shops or plumbers’ merchants.
● If problems are suspected, call in a specialist to survey the flue internally using a video camera.
● Consider having the chimney lined. Flexible stainless-steel flue liners are recommended for older buildings as these cause minimal damage to the chimney and can be removed in the future.
● Remember that relining a flue must be carried out in accordance with building regulations.
Damp
Old chimneys can suffer a variety of damp problems, especially if there is no slate or lead ‘tray’ to prevent water soaking down the stack. Problems may be exacerbated if soot bleeds through the walls causing staining to the decoration within the home.
Action:
● Check junctions between the roof and the chimney to ensure flashing and mortar is sound.
● Ensure back gutters behind chimneys are clear. ● Consider fitting a raincap or cowl to the chimney to prevent rain entering the flue. Chimneys serving inglenook fireplaces may be topped by flagstones raised on bricks.
● Avoid totally blocking an unused flue as residual ventilation is needed for it to remain dry.
Thatch and chimneys
Embers and sparks from chimneys along with defects to the stack itself are a significant cause of thatch fires.
Action:
● Take care lighting and tending fires or stoves.
● Use only dry, well-seasoned wood and run at optimum temperature.
● Ensure a chimney height of at least 1.8 m (6ft) above the thatch.
● Avoid spark arrestors as they increase the risk of fire if not properly maintained and cleaned.
● Ensure flue liners are appropriate and check them regularly.
● Maintain the chimney stack and fully overhaul brickwork exposed during rethatching.
Reducing draughts
Heat loss and draughts through flues when a chimney is not in use can be considerable. A number of products are now available that can be temporarily fitted within the base of the flue. These come in various sizes and include chimney balloons, which are inflated with a pump, chimney umbrellas that open to block the flue, and wool draught excluders that wedge into place. In all cases it is vital to remember to remove them before lighting a fire.
Useful contacts
Chimella - chimney umbrellas.
Tel: 020 8533 3888; chimella.com
Chimney Balloon - pump-up draught excluders. Tel: 01900 817109; chimneyballoon.co.uk
Chimney Sheep - natural wool draught excluders. Tel: 01900 269427; chimneysheep.co.uk
Fireplace.co.uk - services and information.
Tel: 0121 773 7312; fireplace.co.uk
Hepworth - terracotta chimney pots.
Tel: 0844 856 5152; hepworthterracotta.co.uk
HETAS - advice and details of businesses and installers. Tel: 01684 278170; hetas.co.uk
National Association of Chimney Sweeps - index of specialist members. Tel: 01785 336555; nacs.org.uk
Solid Fuel Association - information and advice. Tel: 01773 835400; solidfuel.co.uk
West Meon Pottery - bespoke chimney pots.
Tel: 01730 829434; westmeonpottery.co.uk